This invention relates to a conveyor for a storage and advancing system for loads, particularly palletized loads, and more specifically relates to an improved activating and controlling arrangement for effecting controlled movement and stopping of palletized loads by utilizing deflection of the pallet to assist in controlling the movement and stoppage thereof.
Conveying and storing arrangements are extensively utilized in warehouses, factories and the like for permitting storage and advancing of loads, particularly palletized loads, to a discharge or load-removal station. Gravity-type arrangements are particularly desirable in that they eliminate the need for complex powered driving or advancing mechanisms for the loads, and such gravity systems typically provide a horizontally elongate support track which extends at a slight incline relative to the horizontal to provide for controlled advancing movement of the loads downwardly along the track. Such systems permit storage of significant numbers of palletized loads in a xe2x80x9cfirst inxe2x80x94first outxe2x80x9d system, that is, the loads are positioned on the conveyor system at the upper input end thereof, and are then advanced by gravity downwardly along the slight incline for removal at the other or output end, whereby the oldest load on the conveyor system is the first to be removed.
Systems of the above type have been widely adopted and used for many years, and one example of a system which has met with significant acceptance is illustrated in my U.S. Pat. Nos. 4 205 740 and 4 304 521.
My earlier system is frequently utilized as a first inxe2x80x94first out storage rack and, as diagrammatically illustrated in FIGS. 1-2, includes a generally upright framework 11 which typically defines a plurality of horizontally elongate bays disposed vertically one above another within a column, with a plurality of such columns being typically disposed in side-by-side relation. A storing and gravity-type conveying system 12 is associated with and extends lengthwise along each bay.
The system 12 is independently controlled, and one end 13 thereof defines an input end for accommodating loads, typically palletized loads, and the other end 14 functions as the output or discharge end. A conventional stop device 15 is provided at the output end for engaging the lead load so that removal of the lead load from the storage rack is normally accomplished utilizing a lift device such as a fork lift or other conventional mechanism.
The storage and conveying system 12 includes a substantially identical pair of elongate and generally parallel storing and conveying assemblies 21 which are disposed in sidewardly spaced relationship, and extend lengthwise from the input end 13 so as to terminate at the output end 14. The assemblies 21 extend at a slight decline as they project from the input to the output end, which decline is a small acute angle relative to the horizontal, typically 15xc2x0 or less.
Each storing and conveying assembly includes an elongate track 22 which is rigidly mounted on the frame and extends lengthwise of the bay. The track in the illustrated and preferred construction is formed as an upwardly-opening channel member defined by a bottom wall 23 which extends between and rigidly joins to upwardly projecting and generally parallel side walls 24, whereby the channel member defines therein an upwardly opening channel 25 which extends lengthwise along the track 22. At least one of the track side walls 24 has a support flange 26 fixed to the upper edge thereof and projecting transversely, preferably perpendicularly, outwardly away from the channel 25. In the preferred arrangement a similar said support flange 26 is associated with and projects outwardly from the upper edge of each track side wall 24. The support flanges 26 define thereon generally flat and planar upper surfaces 27 which function as storage and braking surfaces, as explained below. At least one of the support flanges 26, namely the flange which is outermost or remote from the other track 22, is also provided with a further flange 28 which angles upwardly from the outer edge of the respective support flange 26 and hence defines thereon an upper surface 29 which is inclined relative to both the horizontal and vertical, and functions as a load centering surface, as explained hereinafter.
The track 22 associated with each storing and conveying system 21 also has an elongate roller assembly 31 which is disposed and extends lengthwise of the track and is vertically movable relative to the track. This roller assembly 31 includes an elongate support channel 32 which is sized so as to be disposed horizontally between and vertically movable relative to the side walls 24 of the respective track 22. This support channel 32 opens upwardly and has a plurality of support wheels or rollers 33 positioned therein in closely spaced relationship longitudinally throughout the length of the support channel. The rollers or wheels 33 are each disposed for rotation about a respective horizontal axis which extends perpendicularly between the side walls of the support channel 32, whereby the rollers 33 are supported for rotation about axes which are perpendicular to the elongated direction of the respective conveying arrangement and bay. The wheels or rollers 33 are disposed with their upper portions positioned at an elevation slightly above the upper edge of the support channel 32.
The roller assembly 31 is in turn supported on a lifting mechanism 35 which is disposed within the bottom of the main track 22 so as to be confined between the bottom walls of the track 22 and the support channel 32. The lifting device 35 typically comprises an elongate pneumatically-inflatable hose 36, commonly referred to as a fire hose, which extends lengthwise of the track 22 and, when at least partially inflated causes upward lifting of the roller assembly 33, and when at least partially deflated causes lowering of the roller assembly 33. The lifting and lowering of the roller assembly 33 by inflation/deflation of hose 36 is such as to cause the upper profiles of the rollers 33 to be moved between a raised load-engagement position wherein the upper roller profiles are at least slightly above the plane of the brake surfaces 27, and a lowered position wherein the upper profile of the rollers 33 is at or slightly below the plane of the brake surfaces 27. The inflation and deflation of the hose 36 is by a suitable pressure and control arrangement 37 which is well known, one example being described in my earlier ""740 patent, so as to cause the hose 36 to be inflated and deflated in a cyclic or pulsing manner to hence provide for desired control over the gravity-urged movement of loads downwardly along the storing and conveying system.
The loads stored on and moved along the storing and conveying apparatus are typically palletized loads 41, each of which includes a plurality of individual articles disposed on and secured to a pallet 42, such as by a shrink-wrap securement. The pallet typically has edge and center skids or runners projecting downwardly therefrom, which runners are frequently secured to a bottom deck or platform. The edge runners (or the bottom deck if present) are typically disposed for direct supportive engagement with either the rollers 33 or the support surfaces 27.
In operation, when the roller assembly 31 is in its lowered position due to a deflated state of the hose 36, the edge runners bear directly on the support surfaces 27 to maintain the load 41 stationary. Upon inflation of the hose 36, the roller assemblies 31 are moved upwardly so that the rollers 33 engage the pallet runners (or bottom deck) and lift them slightly upwardly from the support surfaces 27, whereupon the gravity-induced force on the pallet downwardly along the conveying system causes the palletized load to advance forwardly due to rotation of the rollers 33. The forward advance will continue until the hose 36 is again deflated, causing the roller assemblies 31 to lower and thus cause the runners to again engage the braking and storing surfaces 27. During the lowering of the palletized load, if the load tends to move longitudinally off center, then the outer edge of the runner may engage the inclined centering surface 29 to thus effectively sidewardly displace and hence effect recentering of the palletized load during the lowering thereof.
While the system described above has proven to provide a highly desirable and successful mode of operation, nevertheless Applicant in a continuing effort to improve on this system has been able to determine that improvements can be made with respect to the overall mechanics as well as the structural and operational simplification thereof, particularly in light of the changing design requirements associated with different types of loads such as those loads employing new lighter weight pallets such as plastic pallets.
More specifically, it is an object of this invention to provide an improved storing and conveying system and process for palletized loads, particularly those loads employing deflectable pallets, whereby only a single activating roller system is required for extension lengthwise along the storage and conveying bay, with the storing and conveying system cooperating generally with the longitudinal center of the pallet and utilizing upward and downward deflection thereof so as to control the moving and stopping thereof, whereby the longitudinal side edge portions of the pallet may at all times remain in proper engagement with support surfaces such as freely rotatable conveyor wheels or rollers.
In the improved system of this invention, as aforesaid, only a single elongate activating mechanism is required for each conveyor or bay, thereby simplifying the number of moving parts as well as the air and/or power requirements, and at the same time permitting the edge portions of the loaded pallet to more easily remain properly engaged with conveyor rollers which are not subject to elevational changes so as to provide for desired load stability.
In the storing and conveying system of the present invention, according to a preferred embodiment thereof, there is provided a sidewardly spaced pair of elongate freely-rotatable roller systems which extend at a slight downward incline and which are maintained in continuous supportive and rolling engagement with the underside of the stringers or legs associated with the longitudinal outer edge portions of the pallet. A single storing and conveying arrangement extends longitudinally generally midway between the pair of conveyor tracks, and cooperates with the longitudinally extending center stringer or legs of the pallet. The storing and conveying arrangement includes a support track having a stationary storage surface for engagement with the lower surface of the stringer or pallet legs to maintain the pallet stationary. The support track also has a roller unit vertically movably mounted thereon and actuatable so that, when raised upwardly the rollers engage the pallet and lift the center portion of the pallet to lift the longitudinally center stringer or legs out of engagement with the support track so as to permit gravity-urged movement of the pallet downwardly along the conveyor arrangement until the lifting mechanism again lowers the center roller assembly. The lifting and lowering arrangement takes advantage of the deflection capability of the center portion of the pallet so that the longitudinal center portion is deflected upwardly by the center roller mechanism when in a moving condition, and when the center roller mechanism is lowered the center longitudinal portion of the loaded pallet deflects downwardly so that the center stringer or legs reengage the support surface. During this upward or downward deflection of the pallet, however, the longitudinal edge portions of the pallet remain in supportive engagement with the pair of side conveyor roller systems.
Other objects and purposes of the present invention will be apparent to persons familiar with arrangements of this general type upon reading the following specification and inspecting the accompanying drawings.